BACKGROUND/AIM: To evaluate the effectiveness of diaphragm matching (DM) for carbon-ion radiotherapy (CIRT) of pancreatic cancer patients and develop a simple method to estimate tumour position. PATIENTS AND METHODS: Treatment planning CTs from 27 pancreatic cancer patients treated with CIRT in our facility were used in this study, and 32 other CT image datasets taken on different days were used for measuring tumour and diaphragm displacements. A correction method (SI-correction) was developed using the coefficient x of the regression line formula for the displacements between the diaphragm and tumour in the superior-inferior direction. The tumour positioning errors of bone matching (BM), DM, and SI-correction were measured. RESULTS: Mean (±standard deviation) absolute errors of BM, DM, and SI-correction were 5.10±3.31, 7.48±4.04, and 4.13±2.51 mm, respectively. DM showed significant differences compared to the other correction methods. CONCLUSION: DM was subject to larger errors than BM. Our correction method improved positional errors. Copyright
BACKGROUND/AIM: To evaluate the effectiveness of diaphragm matching (DM) for carbon-ion radiotherapy (CIRT) of pancreatic cancerpatients and develop a simple method to estimate tumour position. PATIENTS AND METHODS: Treatment planning CTs from 27 pancreatic cancerpatients treated with CIRT in our facility were used in this study, and 32 other CT image datasets taken on different days were used for measuring tumour and diaphragm displacements. A correction method (SI-correction) was developed using the coefficient x of the regression line formula for the displacements between the diaphragm and tumour in the superior-inferior direction. The tumour positioning errors of bone matching (BM), DM, and SI-correction were measured. RESULTS: Mean (±standard deviation) absolute errors of BM, DM, and SI-correction were 5.10±3.31, 7.48±4.04, and 4.13±2.51 mm, respectively. DM showed significant differences compared to the other correction methods. CONCLUSION:DM was subject to larger errors than BM. Our correction method improved positional errors. Copyright